The MFSK16 mode performs well in difficult reception conditions, but it is slow (55 word per minute).

This weekend, we will experiment with the simultaneous transmission of two MFSK16 signals, one on a center frequency of 700 Hz, the other on 2000 Hz. By transmitting the first half of a news story on the left “channel,” and the second half on the right, the speed of MFSK16 is effectively doubled.

The additional speed does come at a price. The transmit power is now divided between the two MFSK16 streams, resulting in a lower signal-to-noise (SNR) ratio for each.

Reception of the two simultaneous transmissions can be accomplished by decoding sequentially from your recording. Or you can run two instances of Fldigi. On one instance of Fldigi, turn the RxID on. On the other, turn the RxID off. The RSID will be transmitted for the 700 Hz MFSK16 transmission and will (we hope) guide your first instance of Fldigi to the correct audio frequency. It will not be transmitted on the 2000 Hz transmission, so use the 20-second tone to tune your second instance of Fldigi to the exact frequency near 2000 Hz. Decoding software must be tuned precisely for successful printout of MFSK16 text.    

Maybe all these steps are not worth the effort, but let’s see what happens.

Here is the lineup for VOA Radiogram 43, 25-26 January 2014 (all modes centered on 1500 Hz except where indicated):

 1:38  MFSK32: Program preview

 3:52  MFSK16: IMF 2014 world economic outlook

 9:32  MFSK16 at 700 and 2000 Hz: Same VOA News story

13:22  MSFK64/Flmsg: Global effects of net neutrality debate,

       with image

20:09  MFSK64: China Internet outage, with image

23:52  MFSK64: Image of Kim shoveling snow

25:42  MFSK32: Closing announcements

 Please send reception reports to radiogram@voanews.com.